While it is clear that the timing concept in Go is well worth a node, for the sake of backlinks alone, it isn't so clear what to put here.
After these joseki plays, Black will play the atari moves at a and b - in some order. Which is correct?
If Black gets the timing wrong, as here, White can exploit the presence of to make a net on the outside with
. Now
is misplaced. We assume that Black connects the ko, since there are no ko threats in the opening.
Black should play the other atari first. In this case White's chance at resistance with c next gives Black an outside ponnuki. White cannot get a good result that way.
Some aspects:
Theoretically speaking, perhaps the game divides up as game temperature model, plus real timing issues which aren't just a question of sente sidetracks.